Bush-type rubber mounts are used for many different purposes in automotive engineering. They are used there, e.g., to mount parts, e.g., for mounting the suspension arms for the wheel suspension. Depending on the particular application, the radial damping intended to be achieved with the rubber mount is frequently also supported by a hydraulically damping fluid, and corresponding hydraulic chambers for accommodating the damping agent are provided for this purpose in the mount body.
Such a hydraulically damping rubber mount is described, e.g., in DE 198 07 949 A1. According to the usual design, the mount described in the document comprises a tubular inner part, a sleeve surrounding the tubular inner part, and the elastomeric mount body, which is arranged in-between and is connected to the inner part by vulcanization. The mount described in the document has a special geometry. Two radially outwardly extending elevations are provided on the circumference of the inner part in an axial section. The mount body is vulcanized to these elevations, and these are walls in the form of elastic, hollow truncated cones in this case, which are supported on the elevations arranged in the axial center of the inner part and connected thus to the outer sleeve both axially as well as radially, i.e., extending quasi diagonally toward the outside relative to the axial direction. According to the explanations given in the document, it is said to be achieved with this comparatively complicated geometry that the radial damping of the mount is determined nearly exclusively by the damping agent circulating in the chambers between the elastic walls and the outer sleeve, while the damping action by the elastomer is basically negligible. Aside from the somewhat complicated geometry, there is a problem in the prior-art solution in that the radial damping characteristic of the mount is adversely affected by cardanic forces occurring. This can be attributed to the fact that a certain displacement of the damping agent from one chamber into the other takes place in the case of cardanic forces even without the effect of the radial forces to be damped due to the torsion or tilting of the inner part as well as the deformation of the elastomeric walls.
Another example for a hydraulic mount is described in DE 196 13 912 C2. The inner part has a radially outwardly extending elevation in the area of the axial center of the mount in this mount as well, at least according to one embodiment variant. The elevation surrounded by the elastomer and bordered by an additional element acts as an abutment with respect to radially acting forces in the mount described in the document. Due to the bordering with the element, the free surface of the abutment is reduced under load, so that the abutment hardens. Concerning the taking into account of cardanic stresses, it is only mentioned in the document that the bilateral foot areas of the abutments are not surrounded by the element in order to provide the possibility of deformations under torsional stress or cardanic stress in this area. However, a defined cardanic axis specifically absorbing the cardanic stress is not given as a result, so that the damping agent contained in the chamber is partially displaced in the case of cardanic stress in this mount as well. As a result, the radial damping action is affected by the cardanic forces in an undesired manner.